The objectives of this research program are to relate the physical-chemical structure of Neisseria gonorrhoeae LPS to its antigenic structures which are immunologically recognized by humans and to use this information to study the epidemiology and immunopathogenesis of gonococcal disease. LPS structure will be deduced from physical measurements of oligosaccharide chain lengths, using isogenic mutants of Salmonella minnesota as size markers, and the molar ratios of carbohydrate constituents and will be confirmed by structural studies. Techniques will include molecular seive and high performance liquid chromatography (HPLC), gas-liquid chromatography (GLC) and 13C-NMR. Antigenic structure will be deduced by inhibition of serological assays, primarily bactericidal and ELISA, and by subtractive affinity (immunosorbant) chromatography. Knowledge of antigenic structure will be used to develop a human-relevant typing system and serological assays for specific antibody. These tools will then be used to study the immunoepidemiology and immunopathogenesis of gonococcal disease. In particular, we will assess the role of complement fixing antibody in the pathogenesis of clinical syndromes.